Keto Peanut Butter Mug Cake

This peanut butter mug cake is made with just 3 ingredients and is completely keto and flourless! Ready in under a minute and full of peanut butter flavor, it’s a delicious low carb and sugar free dessert. 

keto peanut butter mug cake

3 Ingredient Keto Mug Cake

When it comes to keto mug cake recipes, my favorites include a pumpkin mug cake, gingerbread mug cake, and this keto peanut butter mug cake.

Ever since starting a keto diet, peanut butter soon became one of my most used ingredients. Whether it be using it in recipes, snacking on it between meals, or slathering a piece of keto bread with it, it’s safe to say I eat it every single day. 

FACT– I eat peanut butter balls every single day. 

Recently, I’ve been ending my day with various single-serving desserts. Mug cakes have always been my go-to. Recently, I’ve been obsessed with this peanut butter version. 

Unlike most mug cakes out there, this one only needs 3 ingredients! No grains, no flour, and no sugar needed, it’s a low carb way to satisfy my sweet tooth! This mug cake takes less than a minute to make, and is also naturally gluten free!

Ingredients for this recipe

  • Peanut butter– Make sure the peanut butter you use has a smooth and drippy texture. As this is a keto mug cake, you want to be using sugar free peanut butter. 
  • Granulated sweetener– Either monk fruit sweetener or erythritol can be used. I prefer erythritol as for microwave desserts, as it has a better flavor. 
  • Egg– Room temperature egg.
  • Baking powder– Optional, but gives the mug cake that extra fluffiness. 

How do you make a peanut butter mug cake?

Start by whisking together all your ingredients in a small mixing bowl, until a batter remains. Transfer your batter into a microwave safe bowl, ramekin, or mug. Microwave for 45 seconds, to a minute. Remove from the microwave and let sit for a minute, before enjoying it.


Tips to make the best mug cake

  • If you’d like to make this mug cake in the oven, simply bake it at 180C/350F for 8-10 minutes. Be sure the ramekin you use for it is oven safe. 
  • Oven makes and models are different. Your mug cake may take longer than 45 seconds to make. 
  • Do not overbake the mug cake. This is a flourless dessert, so the cooking time is greatly reduced. 
  • You can either use 1 or 2 tablespoons of sweetener. I stick to one tablespoon, as I find it plenty sweet as it is. 
  • If you have a microwave safe cereal bowl, you can use that instead of a ramekin. This is a better option if you are worried that there may be overflow. 

Flavor and dietary Variations

  • Peanut Butter Chocolate Chip– As pictured. Add 1-2 teaspoons of keto chocolate chips to the batter and on top of the mug cake. 
  • Chocolate Peanut Butter– Add 1-2 tablespoons of cocoa powder to the batter. 
  • Peanut butter and jelly– Swirl through 1-2 teaspoons of your favorite jelly or jam into it. 
  • Vegan peanut butter mug cake– Replace the egg with 1/4 cup all purpose flour and 1/4 cup plant based milk. 
  • Paleo peanut butter mug cake– Replace the peanut butter with either almond butter or cashew butter.

peanut butter mug cake

More delicious mug cakes to try

3 ingredient keto mug cake

Peanut Butter Mug Cake (3 Ingredients!)

This keto peanut butter mug cake is made with just 3 ingredients and takes less than a minute to make! Fluffy and full of peanut butter flavor, it's your low carb and sugar free dessert for one!
4.98 from 44 votes
Print Rate
Course: Dessert
Cuisine: American
Prep Time: 1 minute
Cook Time: 1 minute
Total Time: 2 minutes
Servings: 1 mug cake
Calories: 355kcal
Author: Arman



  • In a small mixing bowl, add all your ingredients and whisk together, until combined.
  • Transfer your mug cake batter into a greased microwave-safe ramekin or cereal bowl. Microwave for 45 seconds-1 minute. Remove from the microwave and let sit for a minute, before eating.

Oven Instructions

  • Preheat the oven to 180C/350F. Grease an oven-safe ramekin (6-8 inches) with oil. Make the batter before transferring to the ramekin. Bake for 8-10 minutes.


* Erythritol, monk fruit sweetener, or keto brown sugar can all be used. Use the full 2 tablespoons if you prefer a sweeter mug cake. 


Serving: 1mug cake | Calories: 355kcal | Carbohydrates: 10g | Protein: 18g | Fat: 29g | Sodium: 535mg | Potassium: 381mg | Fiber: 3g | Vitamin A: 270IU | Calcium: 184mg | Iron: 2mg | NET CARBS: 7g
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